This invention relates to a process for the production of polyisocyanate addition products in which ammonium salts are employed as latent, heat-activatable catalysts. The present invention also relates to storage stable formulations containing such latent catalysts.
Catalysts for the isocyanate polyaddition process are known. Such catalysts include, for example, tertiary amines such as triethylene diamine (sold under the trademark Dabco) and organotin compounds such as tin-(II) octoate. Other examples of known catalysts are described, for example, on pages 26 to 29 and 31 to 33 of German Offenlegungsschrift No. 2,854,384.
Information on the mode of action of such catalysts can be found in Kunststoff-Handbuch, Vol. VII, by Vieweg and Hochtlen, Carl-Hanser-Verlag, Munich, 1966, for example on pages 96 to 102.
These known catalysts are generally used in a quantity of from about 0.001 to 10 wt. %, based on the total quantity of compounds containing at least two isocyanate-reactive hydrogen atoms.
One disadvantage of these known catalysts lies in the fact that they show substantially constant activity at temperatures from about 20 to 120.degree. C. Consequently, it is not possible to produce formulations containing these catalysts, polyols and polyisocyanates having an increased pot life because the catalysts accelerate the isocyanate addition reaction at temperatures as low as room temperature.